Why is the attribute nsaccountlock a multi-value?

Hi all,

In an application I'm currently developing I'm using the internal 
attribute nsaccountlock to lockout accounts. While trying to set the 
attribute I ran into trouble since it is a multi value: the result was 
that a account at one point had the nsaccountlock attribute set to  
"null, true" (mutli-value).
I solved the problem by altering 00-core.ldif (sorry) and make the 
nsaccountlock a single value because I can't think of a scenario in 
where you would want to have the account status set to multiple values. 
Since then I've not run into trouble and I'm testing it now in a MM 
environment (starting to test it)
Does anyone have any experience with this approach or can someone point 
out the risks I'm taking with this?
regards,

Arjan